The following relates generally to wireless communication, and more specifically to channel access mechanisms for multi-band operation.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform-spread-OFDM (DFT-S-OFDM). A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
In wireless communications systems supporting communications over multiple frequency bands, higher frequencies may generally experience larger degrees of signal attenuation. For example, millimeter wave (mmW) communications may experience substantially lower coverage in non-line-of-sight (NLOS) channels (e.g., compared to sub-6 GHz communications). Additionally, mmW deployments may provide sparser coverage (e.g., larger or more regular coverage gaps) than low-band deployments. In some cases, unlicensed mmW communications may be associated with stricter effective isotropic radiated power (EIRP) regulations than licensed or shared spectrum communications. For example, the 60 GHz unlicensed band may limit transmission power to 40 dBm per device while the 37 GHz shared band may allow transmission powers up to 75 dBm per 100 MHz per device. Additionally or alternatively, maximum permissible exposure (MPE) restrictions may limit the achievable data rate and/or communication coverage at certain high-band (e.g., mmW) frequencies (e.g., for both unlicensed and licensed channels).
Power consumption in mmW devices may be dominated by the radio frequency (RF) components, which may dissipate power due to lower efficiencies associated with operation at higher frequencies. Additionally, stand-alone cellular design approaches may be ineffective for mmW deployments (e.g., due to the low achievable inter-site distances (ISDs) which may create signal interference for communications over frequencies that experience lower degrees of signal attenuation). Therefore, while communications over higher frequency bands may experience benefits (e.g., greater bandwidth), such benefits may in some cases be offset by the resource cost. Improved techniques that support multi-band operation may be desired.